This is the second time in the series that an Ingalls has quit teaching in Walnut Grove because of Harriet's interference. Rememember that Caroline did the same thing in Season 1's "School Mom," where she substituted temporarily for Miss Beadle.
Reply: Mrs. Oleson also became the temporary substitute when both Caroline and Laura quit. However, it appears that a stronger opinion regarding Mrs. Oleson's unfit teaching skills developed during School Mom, in which Nellie and Willie were the only children to show up for class when Mrs. Oleson got the job. Interestingly, though, 6 years later, it doesn't seem as though any parent objected initially to having Harriet teach their children in Good Bye, Mrs. WilderSchool Mom.